Radeon HD 7970: One GPU to rule them all

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Spend any serious amount of time with computers, especially building them, and it becomes much easier to see the pieces rather than the whole. Obsessing over whether this memory is fast enough or that hard drive is big enough or some other motherboard is better for overclocking than the one you’re looking at, for better or worse, goes with the territory. But the encroaching end of a calendar year always inspires some reflection, and looking back on 2011 it’s easy to see how things on the video side of the personal computing universe started becoming more alike more quickly than many of us anticipated in the waning days of 2010.

With the unveiling of its Radeon HD 7970 video card today (which is slated for wide release on January 9), AMD is taking yet another step toward making CPUs and GPUs indistinguishable from each other. Like the Fermi architecture that has characterized Nvidia’s 400- and 500-series cards, the “Graphics Core Next” innovation of the Southern Islands cards, of which the 7970 is the inaugural representative, is at least as much about parallel computing as it is graphics processing. It was one thing when this was just a promise-filled idea, but now it’s a here-to-stay concept that could transform the way we use (and think about) computer hardware.

Technologies like Fermi and Graphics Core Next (GCN) typically grab many of the headlines — and for good reason. Most of us who have been paying attention to home computing products have long considered video cards an entirely separate entity, maybe even a necessary evil. If you want to have truly good-looking and fast-running games, you simply can’t count on the CPU to do everything — and you haven’t been able to for about 20 years. By offloading the most intense workloads to a separate chip, you not only free up the CPU for tasks it’s better designed for, but you get the same kind of dedicated performance on the video side. It’s a win-win.

There are unquestionably lots of performance and usability improvements on the 7970 that gamers will appreciate: Partially Resident Textures, locally based texture data that can be streamed into an application on demand to reduce or eliminate stuttering; ZeroCore Power Technology, which drastically lowers power usage by shutting down a card when the screen blanks (and even works with subsidiary cards in a CrossFireX setup); multiple independent audio streams across each video output; support for HDMI 1.4a, DisplayPort 1.2, and Direct3D 11.1 when Windows 8 comes out; and quite a bit more. Even if you never move beyond gaming graphics, there’s much here to like.

Things like the GCN architecture change the underlying chemistry. Within a single new AMD GPU there can be 32 GCN compute units (CUs), each of which is capable of simultaneously executing instructions from multiple kernels. Each compute unit contains 64 vector units, for a dizzying total of 2,048 stream processors. When this abundant horsepower is applied to a heavy-duty graphics task (which the CUs naturally specialize in), you can move digital mountains; in my personal testing with the 7970 I encountered remarkably high performance in games even at the difficult resolution of 2,560×1,600. But the beauty of this is that you don’t have to limit yourself to graphics or gaming. Apply the same technology to other work, whether rendering video, mining Bitcoins, or cracking passwords, and you have a veritable army of processors at your disposal.

For all intents and purposes, we’re obliterating the upper bound on computing possibility. The benefits of this are tantalizing — it wasn’t that long ago that computers were hardly a household item, and now every individual machine can contain the equivalent of thousands of them — but taking advantage of them will be more difficult, and require a new way of thinking from programmers and users alike. The former group needs to find ever new and better ways to take advantage of the unique capabilities of graphics processors, and the latter needs to stop looking at the video card as a means toward one specific end. The sooner video cards are treated by everyone as computers within computers, the easier it will be to harness their powers for good rather than just good frame rates.

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